The present disclosure generally relates to a method of forming a semiconductor structure, and particularly to a method of performing selective epitaxy of a semiconductor material on semiconductor surfaces in a self-limiting manner.
Some semiconductor devices require a plurality of semiconductor fins including epitaxially deposited semiconductor material portions and not merged among one another. For example, a fin field effect transistor may include a plurality of semiconductor fins. Raised active semiconductor regions (such as raised source regions and raised drain regions) can be formed on physically exposed semiconductor surfaces of the plurality of semiconductor fins after formation of a gate electrode and a gate spacer. In such cases, the raised active semiconductor regions on a neighboring pair of semiconductor fins should not be in physical contact with each other to prevent electrical shorting between the neighboring pair of semiconductor fins.
Due to inherent variations in the pitch, the shapes, and the surface conditions of the semiconductor fins, the rate of growth of epitaxially deposited material in the raised active regions is difficult to control with uniformity, and therefore, merging between neighboring raised active semiconductor regions can occur statistically. Such a merger between neighboring raised active semiconductor materials can result in formation of high growth rate facets, i.e., facets that induce epitaxial deposition at a high growth rate. A significant amount of semiconductor material can be deposited due to deposition on high growth rate facets, thereby providing an undesirable conductive path between neighboring semiconductor fins. Thus, a method for preventing accidental formation of undesirable conductive path between neighboring semiconductor fins is desired.